Process for creaseproofing cellulosic fiber-containing fabric using formaldehyde vapor and a solid and a solid catalyst

ABSTRACT

Cellulosic materials such as cotton fabrics or garments are made crease resistant by exposing them to formaldehyde vapor at an elevated temperature after pre-impregnation of fabric with a formaldehyde-free aqueous solution of a latent catalyst, preferably zinc chloride.

United States Patent [1 1 Wilson et al.

[ PROCESS FOR CREASEPROOFING CELLULOSIC FIBER-CONTAINING FABRIC USING FORMALDEHYDE VAPOR AND A SOLID AND A SOLID CATALYST [75] Inventors: Katherine W. Wilson, Newport Beach; Ronald Swidler, Pasadena;

Jose P. Gamarra, Santa Ana, all of Calif.

[73] Assignee: Cotton, Incorporated, New York,

22 Filed: May 26,1971

21 Appl.No.: 147,201

Related US. Application Data [63] Continuation of Ser. No. 762,135, Sept. 24, 1968,

abandoned.

[52] US. Cl 8/ll5.6, 2/243, 8/ll5.5, 8/1 15.7, 8/1 16.4, 8/129, 8/l44.2, 8/DIG. 4,

8/DIG. 9, 8/DIG. 10, 8/DIG. 21, 34/23,

[51] Int. Cl. D06m 13/14, D06m 13/54 [58] Field of Search 8/115.6, 116.4, DIG. 15

[56] References Cited UNITED STATES PATENTS 3,310,363 3/1967 Russell et a1 8/1 16.4 X

[451 Sept. 24, 1974 3,663,974 4/1972 Watanabe et al 8/1 16.4

FOREIGN PATENTS OR APPLICATIONS 291,474 6/1928 Great Britain 8/l16.4

437,642 11/1935 Great Britain 8/1 16.4

OTHER PUBLICATIONS Primary Examiner-George F. Lesmes Assistant ExaminerJ. Cannon Attorney, Agent, or Firm-Burns, Doane, Swecker & Mathis t [5 7] ABSTRACT Cellulosic materials such as cotton fabrics or garments are made crease resistant by exposing them to formaldehyde vapor at an elevated temperature after preimpregnation of fabric with a formaldehyde-free aqueous solution of a latent catalyst, preferably zinc chloride.

11 Claims, No Drawings PROCESS FOR CREASEPROOFING CELLULOSIC FIBER-CONTAINING FABRIC USING FORMALDEIIYDE VAPOR AND A SOLID AND A SOLID CATALYST CROSS-REFERENCE TO RELATED APPLICATION This application is a continuation of copending application Ser. No. 762,135, filed Sept. 24, 1968, now abandoned.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to the creaseproofing of cellulosic materials.

2. State of the Art It is old in the art to creaseproof cellulosic materials and increase their wrinkle resistance by treatment with formaldehyde. However, the simpler ones of such prior treatments have tended to cause a serious degradation of tensile strength, abrasion resistance and other desirable properties of the fabric. Other such processes heretofore designed to overcome such disadvantages have been difficult to carry out in commercial practice because of the special conditions required to be maintained or because of the multiplicity of consecutive steps required or because of other complications.

SUMMARY OF THE INVENTION Therefore, an object of this invention is to improve the wrinkle resistance of cellulose by the use of formaldehyde in a relatively simple process without seriously degrading other important fabric properties such as tensile strength and abrasion resistance.

Another object is to provide a process wherein formaldehyde is distributed in the fabric with a high degree of uniformity and reproducibility.

A more specific object is to provide a process wherein the fabric need not be padded with a treating bath more than once and wherein it is exposed to formaldehyde in the vapor phase.

Another specific object is to provide a process wherein the fabric may be effectively pressed with a hot iron after padding with a latent catalyst and wherein the pressed fabric may thereafter be crease-proofed by exposure to formaldehyde vapor.

These and other objects, as well as the nature, scope, and operation and utility of the invention will become more clearly apparent from the following description and appended claims.

In accordance with the present invention a process is provided for creaseproofing cellulosic fiber-containing fabric using formaldehyde vapor and a solid catalyst, which process involves (a) impregnating the cellulosic fabric to a wet pick up of between about 50 and 110 percent with a formaldehyde-free aqueous solution containing about 0.2 to 5 percent of a water soluble solid catalyst such as zinc chloride, ammonium chloride, phosphoric acid or zinc nitrate, (b) conditioning the formaldehyde-free, catalyst-containing fabric by adjusting the moisture content thereof to between about 5 and 15 percent, preferably between about 5 and 12 percent, exposing the conditioned, formaldehyde-free, catalyst-containing fabric to formaldehyde vapor at a temperature between about 90C. and 150C. until a dry add-on of formaldehyde of between about 0.5 and is affixed to the fabric and the cellulose therein is creaseproofed, and (d) removing any uncombined formaldehyde polymer from the creaseproofed fabric.

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the present invention the dimensional stability, crease resistance and smooth drying characteristics of a cellulosic fiber-containing material are improved with a minimum of degradation of other properties by applying to the material a solution of a latent catalyst and thereafter exposing the catalyst-containing fabric or articles made therefrom to formaldehyde vapor at a temperature between about and C. after having conditioned that fabric to a moisture content of between about 5 and 15 percent based on dry fabric weight. The process requires curing times of only a few minutes and produces excellent wrinkle recovery characteristics as well as high extensibility. Polymers capable of forming a soft film may be included in latex form in the catalyst bath to further improve final fabric properties.

It has been particularly discovered that only few of the acid or acid-forming latent catalysts known in the art of creaseproofing cellulose with urea-formaldehyde type resins are suitable for use in the present process in conjunction with gaseous formaldehyde if superior results are to be achieved. More particularly, it has been found that citric acid, sulfamic acid and sodium dihydrogen phosphate, for instance, give little or no improvement in wrinkle recovery if used as latent catalysts in a procedure such as that required in the present invention. Magnesium chloride, which is another popular creaseproofing catalyst, also gives only a modest improvement and requires relatively long processing times when using gaseous formaldehyde as the creaseproofing agent.

In contrast, zinc chloride, ammonium chloride, phosphoric acid and zinc nitrate have been found effective when applied to a properly moisture conditioned fabric, and among these zinc chloride has been found to be particularly outstanding and free from collateral disadvantages. For instance, in comparison with zinc chloride, phosphoric acid results in a greater degree of fabric degradation, especially if permitted to remain in the fabric for a long time between its initial impregnation and its final removal by laundering subsequent to curing. Ammonium chloride, in comparison with zinc chloride, has the advantage of being very fast acting but has the disadvantage of decomposing at elevated temperatures and therefore is not very effective where it is desired to hot press the fabric prior to exposure to the formaldehyde vapor and final cure. The latter drawback also applied to the use of zinc nitrate. If the catalyst is decomposed in the fabric before the latter is exposed to formaldehyde and cured, the resulting creaseproofing is relatively limited and only very low wrinkle recovery values are obtained. Moreover, in the case of a nitrate salt decomposition produces nitrogen dioxide, a strongly oxidizing substance, which tends to depreciate fabric properties such as tensile strength.

After fabric has been cured to the optimum extent, it maybe washed and dried to make it ready for use. Any formaldehyde polymer that is left on the treated fabric at the end of the curing step and any subsequent operation such as laundering, may be easily and permanently removed therefrom by drying or heating the washed fabric, e.g., in air, at a temperature above 100C., preferably between 1 and 150 C., whereby uncombined formaldehyde polymer is depolymerized and removed and liberation of irritating formaldehyde from the fabric during subsequent use is precluded. This is in contrast to the behavior of ureaformaldehyde resins such as are commonly used for creaseproofing, which tend to decompose slowly and thus release formaldehyde gradually from treated fabrics during service.

As already mentioned, it is often advantageous in the practice of this invention to include in the catalyst bath a polymeric resinous additive that is capable of forming a soft film. For instance, such additive may be a latex or fine aqueous dispersion of polyethylene, various alkyl acrylate polymers, acrylonitrile-butadiene copolymers, deacetylated ethylene-vinyl acetete copolymers (polyvinyl alcohols), polyurethanes and. so forth. Polymeric additives suitable for this general purpose are otherwise well known in the art and in most cases are commercially available in concentrated aqueous latex form. For use in the present invention such a latex is preferably diluted to provide about 1 to 3 percent polymer solids in the aqueous padding bath before the fabric is treated therewith.

The present invention is useful for treating various natural or artificial cellulosic fibers alone or as mixtures with each other in various proportions or as mixtures with other fibers. They include natural cellulosic fibers such as cotton, linen and hemp, as well as regenerated or artificial cellulosic fibers such as viscose rayon and cuprammonium rayon. Other fibers which may be used in blends with one or more of the above mentioned cellulosic fibers are, for example, cellulose acetate, polyamides (e.g., nylon), polyesters (e.g., polyethylene terephthalate), polyacrylonitrile, polyolefins (e.g., polypropylene), polyvinyl chloride, polyvinylidene chloride, and polyvinyl alcohol fibers. Such blends preferably include at least per cent by weight, and most preferably at least 60 per cent by weight, of cotton or natural cellulose.

The fabric may be knit, woven, nonwoven, or otherwise constructed. It may be fiat, creased, pleated, hemmed, or formed into most any shape prior to contact with the formaldehyde-containing atmosphere. After processing; the formed creaseproofed fabric will maintain the desired configuration substantially for the life of the article, that is, a wash-wear or durable press fabric will be produced.

To treat a fabric with gaseous formaldehyde in accordance with the present invention, the fabric containing a previously applied latent catalyst may be placed in a reaction chamber to which gaseous formaldehyde is supplied from any convenient source, e.g., a formaldehyde generator wherein formaldehyde vapor is produced by heating a suspension of para-formaldehyde in mineral oil. The reaction chamber is preferably maintained at a temperature between about 90 and 150 C e.g., between 110 and 130 C. The atmosphere in the reaction chamber may either consist essentially of formaldehyde or it may be a mixture containing from 5 to 75 volume per cent formaldehyde gas diluted with air or an inert gas such as nitrogen. A formaldehyde addon of between about 0.5 and 5 percent based on dry fabric weight should thus be affixed, whereupon the cured fabric may be scoured with an aqueous detergent solution to remove any water soluble formaldehyde and other soluble matter.

To contact the fabric with the gaseous formaldehyde any suitable means may be employed. For example, a batch system utilizing a closed vessel or tube containing the gaseous formaldehyde may be used in which the catalyst-containing fabric either in its flat state or in the form of a tailored garment may be placed for the appropriate time. In the alternative, a dynamic or continuous system can be used such as one wherein a stream of formaldehyde vapor is passed through a closed elongated chamber through which the fabric is also passed at an appropriate rate, either concurrently or countercurrently relative to the formaldehyde vapor or gas mixture. It is also possible to use combinations of the above, such as by passing a stream of formaldehydecontaining gas over a stationary fabric.

To illustrate the present invention a number of tests has been performed and will be described below.

The reactor used in this work was a cylindrical vessel having a capacity of about 71 liters, constructed of Vet-inch aluminum (42 cm. inside diameter and 57 cm. high). The walls of this reactor are heated with band heaters equipped with a 3-way switch that permits operation at 600, 1200 or 2400 watts. The reactor wall temperature is controlled by an adjustable bimetallic thermostat, and the reactor is surrounded by an insulating blanket. The gas content of the reactor is recircu lated through an external recycle line by an aluminum pressure blower equipped with a heat slinger and hightemperature, lubricated sealed bearings. An adjustable damper in the recycle line permits some control of the pressure within the reactor, but during normal operation nearly atmospheric reactor pressure is preferred.

Formaldehyde gas is conducted into the reactor through a heated line from a separate vessel where it is generated as needed by heating a suspension of paraformaldehye in mineral oil. The reactor is further equipped with another line through which other gases such as steam or air may be admitted when and as desired. The rate of flow of formaldehyde was controlled by regulating the temperature of the mineral oil between and 140 C.

EXAMPLE 1 A series of tests was conducted in treating printclotrf with solutions of various solid catalysts, with and without a polymeric additive, at a wet pick-up of about 70 percent, drying the fabric and conditioning it to a moisture content of about 10 percent, then exposing it to formaldehyde in the reaction chamber described above at C. for various reaction times, and finally washing and drying the cured fabric. The results are presented in Table l.

The tabulated data show that with proper control, satisfactory cross-linking is accomplished with ammonium chloride in a reaction time of 1 to 2 minutes, giving fabrics which possess satisfactory wrinkle recovery values and tear strengths. With zinc nitrate somewhat longer reaction times, e.g., 5 to 6 minutes, give optimum results under comparable conditions and actually tend to give better Percent Area Moisture dried shrinkage regain Crease retention Wash-wear rating rating Line Tumble Line dried dried dried Tensile propertiesnt conditioned Stoll Extenflex Work-tosion at Tensile abrasion rupture break, strength Tumble (in.-lb.) percent (1b.)

TABLE II.NOVEL FORMALDEI-IYDE TREATMENT COMPARED WITH CONVENTIONAL RESIN TREATMENT Percent l (1 bath corn osi- Moisture tion, perce dt content Wrinkle recovery Reaction before angle (W F) 36832618 ma- Zinc time treats r ir e h 183 nitrate min. ment Addpn Dry Wet grams (cycles N.a. 172 147 770 N.a. 122 127 750 291 Sample designation Untreated control (unwashed)... Untreated control (washed) Formaldehyde treatment (ZnCh):

cm. mind Inn:

cow l e Inn tear strengths and flex abrasion than ammonium chloride at comparable wrinkle recovery levels. However, attempts to prepare durable press trouser cuffs from the zinc nitrate catalyzed fabric were not successful because the catalyst was decomposed in the fabric by the hot iron used to press the creases into the uncured fabric and consequently only very low wrinkle recovery values were obtained when such creased fabrics were later treated with formaldehyde vapor.

10 In other tests, a comparative evaluation was made of the properties of fabrics creaseproofed with gaseous formaldehyde using zinc chloride catalyst and of fabrics cross-linked with one of the most prevalent commercial systems comprising dihydroxy-dimethylol ethylene urea (Permafresh 183) using zinc nitrate catalyst at comparable degrees of wrinkle recovery. The fabrics treated with gaseous formaldehyde have been found to have greater extensibility at break than the conventionally treated fabrics, a high wet and dry wrin kle recovery angle with a concommitant high moisture regain, and high wash-wear and crease retention ratings when either line or tumble dried. Excellent results were obtained not only with printcloth but also with oxford cloth, and increased tear and tensile strength retensions were noted when the treated fabrics were woven from mercerized yarn.

Some of the characteristic tests and data obtained are described in the next example.

3 r EXAMPLE? Cotton printcloth was creaseproofed using the formaldehyde-zinc chloride system and the commercial dihydroxy-dimethylol ethylene urea (DHDMEU)- zinc nitrate system using the following procedures.

A. For the formaldehyde-zinc chloride system fabric samples were padded to a wet pick-up of 65 percent with an aqueous solution containing 3.2 percent (solids) of Rhoplex K-87 acrylic resin emulsion and 4 0 percent zinc chloride, dried slack for 3 minutes at 80 C., steam ironed, conditioned overnight in an atmosphere of 65 percent relative humidity (moisture content of fabrics was approximately 7 percent), and then exposed to formaldehyde vapor for varying lengths of time at 105 C. Properties of these fabrics were determined after one and ten laundering cycles.

B. For the DHDMEU-zinc nitrate system, fabric samples were padded to a wet pick-up of 65 percent with aqueous solutions containing varying concentrations of Permafresh 183 (DI-IDMEU). All pad bath solutions contained 3.2 percent (solids) Rhoplex K-87 acrylic resin emulsion, based on the total weight of the solution, and 3.3 percent zinc nitrate, based on the weight of the Permafresh 183 solution. The fabrics were dried slack for 5 minutes at C. and cured at C. for 5 minutes. Properties of fabrics were determined after one and ten laundering cycles. The results were presented in Table II.

One of the important differences between the fabrics 0 treated with formaldehyde and with DHDMEU is the high extensibility of the former.

Wash-wear and crease retention ratings measured after tumble drying were more or less similar for both systems, but after line drying the formaldehyde treated fabrics were decidedly superior to those treated with 'DHDMEU. Fabrics creaseproofed with gaseous formaldehyde catalyzed by zinc chloride showed excellent durability to laundering, maintaining the same dry and wet wrinkle recovery angles throughout l laundering cycles. The DHDMEU-treated fabrics did not perform quite as well in this respect as the samples catalyzed with zinc chloride. Particularly outstanding durable press performance after repeated Fabric properties Reaction Formal Wrinkle recovery time at dehydo (W+F), deg. Tum- Stoii Hex 120 C. content, strength, abrasion, Catalyst Additive min. percent. Dry K. m

Untreated prliltcloth s 3 130 810 400 Ammonium ch1oridc None (water only) 26g 3 320 140 291 290 240 70 .do... 7 294 240 60 289 289 360 190 t 300 270 330 150 281 264 700 1,410 r 314 278 390 500 .do 327 353 430 L310 0 .do 1 300 313 570 1, 310 Armnonium chloride... Rhoplex K-ST 2 (3.2% so11ds). 231 260 Do 09 290 420 $10 Zinc nitratc..... ..do 296 314 480 1, 610

Do d0 302 323 410 1, 550 Ammonium chlo Urethane latex E502 (3 solids 258 314 370 620 o do.. 294 319 300 270 d 282 319 510 2, 110 292 313 560 2, 760 304 297 460 1, 050 305 272 420 790 261 278 620 2,020 314 299 520 1,770

TE ITEELiORMALbEEvDE'colic Usnvo vaaioos soLiD cA'raLYsTs wherein the uncombined formaldehyde polymer is removed from the creaseproofed fabric by heating at a temperature above 100C.

3. A process according to claim 1, wherein the fabric is a cotton fabric and the catalyst is zinc chloride.

1 Acrylic resin. 2 Acrylic resin. 3 Polyurethane.

4 Deacetylated ethylene-vinyl acetate copolymer. I

Pad baths contained 0.5% ammonium chloride or 2% zinc nitrate hexahydrate.

launderings was observed in the case of oxford clo th treated by the formaldehyde-zinc chloride system in accordance with this invention. Specific fabric construction may have a distinct effect on the resultant properties of fabrics creaseproofed with a given system.

It should be understood that while the foregoing specification describes the general principles and nature as well as preferred embodiments and modifications of the present invention, still other modifications are possible and may be made by those skilled in the art without departing from the scope and spirit of this invention. The invention for which protection is sought is particularly pointed out and claimed in the appended claims.

We claim:

1. A process for creaseproofing cellulosic fibercontaining fabric using formaldehyde vapor and a solid catalyst, which process comprises:

a. impregnating a cellulosic fiber-containing fabric to a wet pick-up of between about 50 and 1 percent with a formaldehyde-free aqueous solution consisting essentially of water which has dissolved therein about 0.2 to 5 percent of a water-soluble solid catalyst selected from the group consisting of zinc chloride, ammonium chloride, phosphoric acid and zinc nitrate,

b. conditioning the formaldehyde-free, catalystcontaining fabric by adjusting the moisture content thereof to between about 5 to percent based on the weight of dry fabric,

0. exposing the conditioned, formaldehyde-free, catalyst-containing fabric to formaldehyde vapor at a temperature between about 90C. and 150C. until a dry add-on of formaldehyde of between about 0.5 and 5 percent is affixed to the fabric and the cellulose therein is creaseproofed, and

d. removing any uncombined formaldehyde polymer from the creaseproofed fabric.

2. A process according to claim 1, wherein the fabric is a cotton fabric and the catalyst is zinc chloride, and

Dry add-on after washing of fabric.

4. A process according to claim 1 wherein the uncombined formaldehyde polymer is removed from the creaseproofed fabric by washing the fabric.

5. A process according to claim 1 wherein the uncombined formaldehyde polymer is removed from the creaseproofed fabric by heating the fabric.

6. A process for creaseproofmg cellulosic fibercontaining fabric using formaldehyde vapor and a solid catalyst, which process comprises:

a. impregnating a cellulosic fiber-containing fabric to a wet pick-up of between about 50 and 1 10 percent with a formaldehyde-free aqueous solution consisting essentially of water which has dissolved therein about 0.2 to 5 percent of a water-soluble solid catalyst selected from the group consisting of zinc chloride, ammonium chloride, phosphoric acid and zinc nitrate, and about i to 3 percent of a finely divided, soft film forming polymer selected from the group consisting of polyethylene, alkyl acryiate polymers, acrylonitrile-butadiene copolymers, polyvinyl alcohols and polyurethanes,

b. conditioning the formaldehyde-free, catalystcontaining fabric by adjusting the moisture content thereof to between about 5 to 15 percent based on the weight of dry fabric,

c. exposing the conditioned, formaldehydefree catalyst-containing fabric to formaldehyde vapor at a temperature between about C. and C. until a dry add-on of formaldehyde of between about 0.5 and 5 percent is affixed to the fabric and the cellulose therein is creaseproofed, and

d. washing the resultant fabric to remove watersoluble solids therefrom.

7. A process for creaseproofing cellulosic fibercontaining fabric using formaldehyde vapor and a solid catalyst, which process comprises:

a. impregnating a cellulosic fiber-containing fabric to a wet pick-up of between about 50 and 1 l0 percent with a formaldehyde-free aqueous solution consisting essentially of water which has dissolved therein about 0.2 to percent of a water-soluble solid catalyst selected from the group consisting of zinc chloride, ammonium chloride, phosphoric acid and zinc nitrate, and about 1 to 3 percent ofa finely divided, soft film forming polymer selected from the 5 group consisting of polyethylene, alkyl acrylate polymers, acrylonitrile-butadiene copolymers, polyvinyl alcohols and polyurethanes,

conditioning the formaldehyde-free, catalystcontaining fabric by adjusting the moisture content thereof to between about 5 to percent based on the weight of dry fabric, c. exposing the conditioned, formaldehyde-free, catalyst-containing fabric to formaldehyde vapor at a temperature between about 90C. and 150C. until a dry add-on of formaldehyde of between about 0.5 and 5 percent is affixed to the fabric and the cellulose therein is creaseproofed, and d. removing any uncombined formaldehyde polymer from the creaseproofed fabric. 8. A process for creaseproofing cellulosic fibercontaining fabric using formaldehyde vapor and a solid catalyst, which process comprises:

a. impregnating a cellulosic fiber-containing fabric to a wet pick-up of between about 50 and 1 10 percent with a formaldehyde-free aqueous solution containing about 0.2 to 5 percent of a water-soluble solid catalyst selected from the group consisting of zinc chloride, ammonium chloride, phosphoric acid and zinc nitrate,

b. conditioning the formaldehyde-free, catalystcontaining fabric by adjusting the moisture content thereof to between about 5 and 15 percent based on the weight of dry fabric,

c. exposing the conditioned, formaldehyde-free, catalyst-containing fabric to formaldehyde vapor at a temperature between about 90C. and 150C. until a dry add-on of formaldehyde of between about 0.5 and 5 percent is affixed to the fabric and the cellulose therein is creaseproofed,

d. heating the resultant fabric to remove any uncombined formaldehyde polymer therefrom,

and wherein prior to step (b) the catalyst-containing fabric is dried and a shaped garment having at least one hot pressed crease formed therein is manufactured from the dried fabric.

9. A process for creaseproofing cellulosic fibercontaining fabric using formaldehyde vapor and a solid catalyst, which process comprises:

a. impregnating a cellulosic fiber-containing fabric to a wet pick-up of between about 50 and 1 10 percent with a formaldehyde-free aqueous solution containing about 0.2 to 5 percent of a water-soluble solid catalyst selected from the group consisting of zinc chloride, ammonium chloride, phosphoric acid and zinc nitrate,

b. conditioning the formaldehyde-free, catalystcontaining fabric by adjusting the moisture content thereof to between about 5 and 15 percent based on the weight of dry fabric,

c. exposing the conditioned, formaldehyde-free, catalyst-containing fabric to formaldehyde vapor at a temperature between about 90C. and 150C. until a dry add-on of formaldehyde of between about 0.5 and 5 percent is affixed to the fabric and the cellulose therein is creaseproofed,

d. removing any uncombined formaldehyde polymer from the creaseproofed fabric,

and wherein prior to step (b) the catalyst-containing fabric is dried and a shaped garment having at least one hot pressed crease formed therein is manufactured from the dried fabric.

10. A process according to claim 9, wherein the fabric is a cotton fabric and is dried to have a moisture content of between about 5 and 12 percent after impregnation with the catalyst solution and before expo- ;sure to formaldehyde.

11. A process according to claim 9, wherein the uncombined formaldehyde polymer is removed from the creaseproofed fabric by washing the resultant fabric to remove water-soluble solids therefrom.

UNETED STATES PATENT FEFEQE @ERTWHQAEE @5 1 QGREQ'MQ Patent No. 3,837,799 Dated September 24, 1974 h Katherine W, Wilson Ronald Swidler, Jose P. Gamarra Invenrods) it is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

IN THE- yre Correct the title of the invention to read PROCESS FOR CREASEPROOFING CELLULOSIV, FIBER-CONTAINING FABRIC USING FORMALDEHYDE VAPOR AND A SOLID CATALYST Signed and sealed this 25th day of November 197 (seer) ACEQEQ:

MeQGY My mason in, c; MARSHALL DANN Arresting Qffieer Commissioner of Patents powso (169) USCOMM-DC 60376-P69 J .5. GOVERNMENT PRINTING OFFICE 1 959 0"556'35 

2. A process according to claim 1, wherein the fabric is a cotton fabric and the catalyst is zinc chloride, and wherein the uncombined formaldehyde polymer is removed from the creaseproofed fabric by heating at a temperature above 100*C.
 3. A process according to claim 1, wherein the fabric is a cotton fabric and the catalyst is zinc chloride.
 4. A process according to claim 1 wherein the uncombined formaldehyde polymer is removed from the creaseproofed fabric by washing the fabric.
 5. A process according to claim 1 wherein the uncombined formaldehyde polymer is removed from the creaseproofed fabric by heating the fabric.
 6. A process for creaseproofing cellulosic fiber-containing fabric using formaldehyde vapor and a solid catalyst, which process comprises: a. impregnating a cellulosic fiber-containing fabric to a wet pick-up of between about 50 and 110 percent with a formaldehyde-free aqueous solution consisting essentially of water which has dissolved therein about 0.2 to 5 percent of a water-soluble solid catalyst selected from the group consisting of zinc chloride, ammonium chloride, phosphoric acid and zinc nitrate, and about 1 to 3 percent of a finely divided, soft film forming polymer selected from the group consisting of polyethylene, alkyl acrylate polymers, acrylonitrile-butadiene copolymers, polyvinyl alcohols and polyurethanes, b. conditioning the formaldehyde-free, catalyst-containing fabric by adjusting the moisture content thereof to between about 5 to 15 percent based on the weight of dry fabric, c. exposing the conditioned, formaldehyde-free catalyst-containing fabric to formaldehyde vapor at a temperature between about 90*C. and 150*C. until a dry add-on of formaldehyde of between about 0.5 and 5 percent is affixed to the fabric and the cellulose therein is creaseproofed, and d. washing the resultant fabric to remove water-soluble solids therefrom.
 7. A process for creaseproofing cellulosic fiber-containing fabric using formaldehyde vapor and a solid catalyst, which process comprises: a. impregnating a cellulosic fiber-containing fabric to a wet pick-up of between about 50 and 110 percent with a formaldehyde-free aqueous solution consisting essentially of water which has dissolved therein about 0.2 to 5 percent of a water-soluble solid catalyst selected from the group consisting of zinc chloride, ammonium chloride, phosphoric acid and zinc nitrate, and about 1 to 3 percent of a finely divided, soft film forming polymer selected from the group consisting of polyethylene, alkyl acrylate polymers, acrylonitrile-butadiene copolymers, polyvinyl alcohols and polyurethanes, b. conditioning the formaldehyde-free, catalyst-containing fabric by adjusting the moisture content thereof to between about 5 to 15 percent based on the weight of dry fabric, c. exposing the conditioned, formaldehyde-free, catalyst-containing fabric to formaldehyde vapor at a temperature between about 90*C. and 150*C. until a dry add-on of formaldehyde of between about 0.5 and 5 percent is affixed to the fabric and the cellulose therein is creaseproofed, and d. removing any uncombined formaldehyde polymer from the creaseproofed fabric.
 8. A process for creaseproofing cellulosic fiber-containing fabric using formaldehyde vapor and a solid catalyst, which process comprises: a. impregnating a cellulosic fiber-containing fabric to a wet pick-up of beTween about 50 and 110 percent with a formaldehyde-free aqueous solution containing about 0.2 to 5 percent of a water-soluble solid catalyst selected from the group consisting of zinc chloride, ammonium chloride, phosphoric acid and zinc nitrate, b. conditioning the formaldehyde-free, catalyst-containing fabric by adjusting the moisture content thereof to between about 5 and 15 percent based on the weight of dry fabric, c. exposing the conditioned, formaldehyde-free, catalyst-containing fabric to formaldehyde vapor at a temperature between about 90*C. and 150*C. until a dry add-on of formaldehyde of between about 0.5 and 5 percent is affixed to the fabric and the cellulose therein is creaseproofed, d. heating the resultant fabric to remove any uncombined formaldehyde polymer therefrom, and wherein prior to step (b) the catalyst-containing fabric is dried and a shaped garment having at least one hot pressed crease formed therein is manufactured from the dried fabric.
 9. A process for creaseproofing cellulosic fiber-containing fabric using formaldehyde vapor and a solid catalyst, which process comprises: a. impregnating a cellulosic fiber-containing fabric to a wet pick-up of between about 50 and 110 percent with a formaldehyde-free aqueous solution containing about 0.2 to 5 percent of a water-soluble solid catalyst selected from the group consisting of zinc chloride, ammonium chloride, phosphoric acid and zinc nitrate, b. conditioning the formaldehyde-free, catalyst-containing fabric by adjusting the moisture content thereof to between about 5 and 15 percent based on the weight of dry fabric, c. exposing the conditioned, formaldehyde-free, catalyst-containing fabric to formaldehyde vapor at a temperature between about 90*C. and 150*C. until a dry add-on of formaldehyde of between about 0.5 and 5 percent is affixed to the fabric and the cellulose therein is creaseproofed, d. removing any uncombined formaldehyde polymer from the creaseproofed fabric, and wherein prior to step (b) the catalyst-containing fabric is dried and a shaped garment having at least one hot pressed crease formed therein is manufactured from the dried fabric.
 10. A process according to claim 9, wherein the fabric is a cotton fabric and is dried to have a moisture content of between about 5 and 12 percent after impregnation with the catalyst solution and before exposure to formaldehyde.
 11. A process according to claim 9, wherein the uncombined formaldehyde polymer is removed from the creaseproofed fabric by washing the resultant fabric to remove water-soluble solids therefrom. 